President Moon Jae-in said Monday that his administration will halt the construction of new nuclear power plants and will not extend the operations of aging reactors.

These are part of efforts for a nuclear-free energy policy, which he has called for since his presidential election campaign.

At the shutdown ceremony of Korea's first commercial nuclear reactor, Kori 1, Moon said he would overhaul the nation's nuclear power development policy.

"The shutdown of Kori 1 is the beginning of a nuclear-free energy country, a paradigm shift for a safer Korea," Moon said at the ceremony in Gijang, Busan.

With the shutdown as momentum, the President said he hopes the country will reach a consensus on what energy policy Korea needs to follow.

"Korea's energy policy used to pursue low cost and efficiency, while people's lives, safety and environmental sustainability used to be treated lightly," Moon said. "But now it is the general idea that people's lives and safety should be prioritized."

The President said he would review the country's nuclear power development policy completely. "I'll abolish our nuclear-oriented energy policy and seek a nuclear-free era. I'll also scrap plans to build new reactors."

He said nuclear reactors' designated lifespan will not be extended, and he will seek to shut down the Wolsong-1 reactor, whose operational life was extended, as soon as possible after reviewing electricity demand.

"We'll draw up a social consensus as soon as possible over the Shin Kori 5 and 6 reactors, which are being built, after reviewing how much of the construction has been completed, how much we will need to pay in compensation when halting it, and how much electricity power is in reserve," Moon said, implying a halt in construction.

The President also pledged strengthened safety standards for reactors, mainly referring to earthquake-proof measures. He said Korea is not a quake-safe country anymore, citing the 5.8-magnitude temblor in Gyeongju, North Gyeongsang Province, last September. Moon said a nuclear reactor accident caused by an earthquake could be fatal as seen in the Fukushima case in 2011.

Promising he will come up with a nuclear-energy free roadmap soon, Moon said he will foster alternative energy development including new and renewable energy as well as liquefied natural gas, solar power and offshore wind power generation.

"Along with nuclear energy, I'll try to reduced the ratio of coal-fired power generation and instead increase that of natural gas. I'll stop building new coal-fired power plants and shut down 10 old ones within my term."

The President said the shutdown of the Kori 1 reactor can be a chance for new business because the country can get knowhow on the decommissioning of nuclear reactors, adding the demand for decommissioning is growing across the world amid a nuclear-free trend.

Environmental groups generally welcomed Moon's promises.

But residents in Ulju, Ulsan, where the construction of the Shin Kori 5 and 6 reactors is underway, sent a letter to Cheong Wa Dae claiming a suspension would cause losses of 2.5 trillion won and damage the residents due to the cancellation of compensation and employment plans.